Superheater



Sept- 15, 1930- v A. SMITH 1,776,135

SURERHEITER Filed Nov. 24, 1925 Figi.

His ATror-neg Patented Sept. 16, 1930 ITT) UNITED STATES vPATENT OFFICE ARTHUR n. SMITH,

F SC-HENECTADY, NEW YORK, ASSIGNQR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK SUPERHEATER Application led November 24, 1926. Serial No.' 150,604.

' The present invention relates to superheaters such as are used in connection wlth boilers, for example, for superheating the vapor generated in the boiler. The invention is well adapted for use in the superheating of steam in steam boilers and this application of the invention is specifically illustrated in the drawing and described in the specification. It is to be understood, however, that the invention is not limited necessarily to this application.

In the production and utilization of highly superheated steam, that is steam heated to temperatures in excess of 750 F., one of the 7 problems is that of providing containers and l conduits forsteam having temperatures of this order. This is because atsuch high temperatures the material of the container or conduit becomes weakened so that it is ren-.- dered incapable of withstanding the pressure of the steam without becoming overstressed. In this connection, it is more-diflicult to produce such hot steam economically than it is to utilize it for the reason that in the utilization of such steam the temperaturey of the container or conduit, the strength of which isa limiting factor, will always be at a temperature somewhat less than the'steam, whereas in the production of superheated steam the temperature of the container or conduit in which the steam is superheated must always be at a temperature higher than that of the steam. 'Ihe object of my invention is to provide an improved `container or conduit especially adapted for use as a superheater tube in the production of superheated steam, and for a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing, Fig. l is a top plan view of superheater tubes embodying my invention; Fig. 2 is an enlarged view of a portion of one of the tubes shown in Fig. 1; Fig. 3 is a view similar to Fig. 2 of a modification, and Fig. 4 illustrates the arrangement of the tubes in a boiler.

Referring to the drawing, 5 indieates'the furnace walls of a boiler setting, 6 indicates the boiler tubes, 7 indicates the steam drum and 8 indicates superheater tubes which are connected to the steam drum and which embody my invention.

Each superheater tube comprises a central pipe or container 9 surrounding which are spirally-wound pipes 10, pipes 10 being held in spaced relation to pipe or container 9 by suitable spacing means 11. In Figs. l and 2 the spacing means is shown as being in the form of a ribbon formed from suitable material, such as steel, spirally wound edgewise on container or pipe 9. Pipe 10 is wound directly on ribbon 11 and acts through ribbon 11 to reinforce pipe or container 9. Ribbon 11 comprises three strips wound spirally triple pitch and pipe 10 comprises two lengths of pipe wound spirally double pitch. The ribbon and pipe are wound one right hand and the other left hand. Pipe 10, ribbon l1 and container or pipe 9 may be fastened together in any suitable manner such as by means of brazing or welding. rIfhe lengths of pipe 10 are connected at one end to a steam supply header 12 which in turn is connected to the steam space'in drum 7 by a conduit 13. The other ends of the lengths of pipe 10 are connected to the outer end of central pipe 9.

" The inner end of central pipe 9 is connected to a discharge header 14 from which superheated steam is conveyed by a conduit 15.

With the above described arrangement, pipe 10 serves as a reinforcing means for the" walls of pipe 9.

In use, the steam flows from header 12 through the lengths of pipe 10 to the outer end of inner pipe 9 and then through pipe 9 to header 14. The tube as a whole is located in the path of the furnace gases so that the steam 1n passing through the pipes of the tube becomesvsuperheated. rIhe steam flows first through the outer pipe 10 and then through the inner pipe 9 so that the initial superheating takes place in outer pipe 10 'and the final superheating takes place in inner pipe 9. This means that outer pipe 10 has a temperature lower than inner pipe 9. By suitably arranging and proportioning pipes 10 10 will not be heated to a tempera-ture such that it is weakened due to its temperature.

On the other hand, pipe 9 may be heated to a temperature such that the tensile strength of the material from which it is formed will be depreciated but this will be offset by the reinforcement which it obtains from the spirally-wound pipe 10.

Spirally wound ribbon 11 in addition to performing the function of struts or supports between central pipe 9 and outer pipe 10 performs also the function of providing a vmeans for increasing the heat-absorbing sursume for example, that it is desired to superheat steam from 475 to 1000o F. Under these circumstances the arrangement may be such that the steam while passing through pipe 10 will be superheated from the initial temperature of 47 5 F. to a final temperature of the order of 700 F., and while passing through pipe 9 it will be superheated y from an initial temperature of the order of 7 00 F. to the final temperature of 1000o F.

In Fig. 3 is illustrated a modification wherein the struts or supports for outer pipe 16 are in the form of cast rings 17 which surround central pipe 18 and are suitably attached to it and to pipe 16.

In both the arrangements illustrated it will be seen that a central pipe carrying highly superheated steam is reinforced by a surrounding pipe carrying superheated steam of lower temperature through the intermediary of supports or struts which form also means for conveying heat to the steam in the central pipe.

While the invention is especially well adapted for use-as a superheater and has been so illustrated and described, it is to be i understood that it is not limited thereto necessarily but that it may be utilized Wherever found applicable. For example, it may be utilized in any instance wherein it is desired to reinforce a conduit or container which is subjected to fiuid of high temperthat the invention may be carried out by other means.

What I claim as new and desire to secure by-Letters Patent of the United States, is:

1. A superheater tube comprising an inner conduit, supporting struts on said inner conduit, and an outer conduit spirally wound circumferentially extending members arranged edgewise on the conduit, and a conduit spirally wound on said members through which fluid of lower temperature flows.

4. The combination with a conduit through which highly heated Huid fiows, of means for reinforcing it comprising ribbon spil-ally wound edgewise on such conduit, and a` tube spirally wound on said ribbon and through which fluid of lower temperature flows.

5. A superheater tube for a boilerv or the.

lilre, said tube comprising outer and inner pipes through which the fluid to be superheated fiows in series, said inner pipe being provided over a major portion of its length with a plurality of axially spaced radiallyprojecting supports, and said outer pipe being wound thereon to form' a reinforcing means for the inner pipe.

In witness whereof, I have hereunto setv my hand this 23d day of November, 1926. ARTHUR R. SMITH. 

